Vulnerability · Published Jul 14, 2026 · Assigned by GitHub_M
CVE-2026-48801linkify-it: Quadratic algorithmic complexity in LinkifyIt#match scan loop
High 8.7
In plain English
A high-severity regular-expression denial of service in linkify-it from markdown-it. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 34% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
linkify-it is a links recognition library with full Unicode support. Prior to 5.0.1, LinkifyIt.prototype.match, the package's primary public API, has O(N²) algorithmic complexity for inputs containing many fuzzy links or emails because the JavaScript-level scan loop re-slices input and re-runs unanchored regex searches on progressively shorter tails. Any service that synchronously renders untrusted Markdown with linkify:true on a request hot path can inherit a worker-process denial of service triggerable by a tens-of-KB request body. This issue is fixed in version 5.0.1.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu:22.04:LTS | node-markdown-it | no fix listed | UBUNTU-CVE-2026-48801 |
| Ubuntu:24.04:LTS | node-markdown-it | no fix listed | UBUNTU-CVE-2026-48801 |
| Ubuntu:26.04:LTS | node-markdown-it | no fix listed | UBUNTU-CVE-2026-48801 |
| Ubuntu:26.10 | node-markdown-it | no fix listed | UBUNTU-CVE-2026-48801 |
| npm | linkify-it | 5.0.1 | GHSA-22p9-wv53-3rq4 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| markdown-it | linkify-it | < 5.0.1 |
Weakness: CWE-1333 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N